Method for evaluating a wireless link, respective device, computer program and storage medium

ABSTRACT

The present disclosure is directed towards a device and a method for evaluating a wireless link (3) of a wireless node of a customer premises equipment (CPE) device (1, 2) during operation of the CPE device. The device and method includes determining an actual data-rate (33) of the wireless link, determining an available data rate (31) of the wireless link, and calculating a head-room (34) based on a required data rate (30) and the available data rate (31).

TECHNICAL FIELD

The present disclosure relates to the field of wireless nodes andrespective devices communicating with each other via a wirelesscommunication.

BACKGROUND

Access gateways are widely used to connect devices in a home to theInternet or any other wide area network (WAN). Access gateways use inparticular digital subscriber line (DSL) technology that enables a highdata rate transmission over copper lines or optical lines. Residentialgateways, as well as other devices such as routers, switches, telephonesand set-top boxes, are understood in this context as customer premisesequipment (CPE) devices.

Access gateways including wireless technology have a key role in today'shome and professional environments. A mechanism for connecting wirelessdevices to a local area network (LAN) is called Wi-Fi, which is a brandname of the Wi-Fi Alliance for devices using the IEEE 802.11 family ofstandards for wireless data transmission. The IEEE 802.11 standardsdefine two types of wireless nodes, a general wireless device that canconnect to other devices called a station (denoted as STA) and a specialtype of a STA that is in control of the network, namely an access point(denoted AP). A Wi-Fi network, often called a WLAN (wireless local areanetwork), includes an AP with one or several STA connected to the AP.

Due to its flexible and “invisible” nature, a lot of LAN applicationsare utilizing Wi-Fi rather than the classical wired Ethernet approach.This widespread usage of wireless LAN has exposed however a seriousdownside of using a shared medium technology: interference.Interference, both Wi-Fi and non-Wi-Fi related, leads to a degraded userexperience due to the nature of IEEE 802.11. In its most common form,IEEE 802.11 networks apply a medium access method in which collisionsare avoided by sensing that the medium is used (denoted as CSMA-CA). Themedium access method is also commonly known as “listen before talk”,describing the essence of the method. Interference of any nature canhence block the medium and force all nodes to remain silent.

Another impact of interference can be packet loss at the receiver side,leading to a reduction of the physical layer rate. The physical layerrate, also referred to in the following as “TrainedPhyRate” ormodulation rate, relates to the transfer rate on the physical layer ofthe wireless connection. The IEEE 802.11 MAC protocols use rateadaptation mechanisms for evaluating the properties of the wirelesschannel and select an appropriate physical layer rate. In this case, theinterference is not detected by the CCA of the transmitter, but isdecreasing the SINR (Signal to Noise and Interference Ratio) of theWi-Fi packets as seen by the receiver. Typically, Wi-Fi nodes will reactto packet loss by lowering the physical layer rate used towards a morerobust—but slower—physical layer rate in an attempt to increase thechance of successfully transmitting packets.

Therefore, in certain circumstances, the Wi-Fi connection can sufferfrom poor performance and even connection loss. Some of thesecircumstances are obvious and easy to explain to an end user. Forexample, if the distance between the station and the access point is toolarge, then signal levels are low and performance will degrade. Othercircumstances are “invisible” and not understood by the end user, e.g. ahidden node. A hidden node is invisible to some of the nodes of anetwork, leading to a practical failure of the CSMA-CA method, which cancause packet collision/corruption over air. In many cases, the end useris not able to diagnose the problem source and correct the issue.

For in-home Wi-Fi networks, connectivity and performance issues arecorrespondingly one of the main Internet service provider support costsand causes for help-desk calls. Internet service providers are thereforesearching for ways to get a better understanding of the end user'swireless environment including link quality and performance.

SUMMARY

A method for evaluating a wireless link of a wireless node of a customerpremises equipment (CPE) device during operation of the CPE devicecomprises: determining an actual data rate of the wireless link,determining an available data rate of the wireless link, and calculatinga headroom based on the actual data rate and the available data rate.The headroom is calculated in particular by including a differencebetween the available data rate and the actual data rate, wherein theactual data rate is measured by the CPE device.

In an aspect of the disclosure, an assessment value is calculated byincluding a ratio of the actual data rate and the headroom, and/or a sumof the actual data rate and the headroom.

In one embodiment, the ratio of the assessment value is a ratio betweena first constant added to the actual data rate, and a second constantadded to the headroom, wherein the first and the second constants arethe same.

In another embodiment, an assessment value is determined, which is basedon a look-up table.

A computer program, being executable by a processor, comprisesexecutable program code for performing the method.

A non-transitory program storage medium, being readable by a processor,comprises executable program code for performing the method.

A device includes a processor, a memory and a wireless node, wherein theprocessor is adapted to determine an actual data rate of the wirelesslink, determine an available data rate of the wireless link, andcalculate a headroom based on a the actual data rate and the availabledata rate. The device may be, in particular, an access point accordingto IEEE 802.11, for example an access gateway.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present disclosure are explained in moredetail below by way of example with reference to schematic drawings,which show:

FIG. 1 a system diagram illustrating an access point communicating witha station via a wireless communication,

FIG. 2 a chart illustrating a monitor result of a wireless communicationaccording to FIG. 1 ,

FIG. 3 a chart showing the monitor result of FIG. 2 , and illustrating aheadroom,

FIGS. 4 a, 4 b charts illustrating assessment values of a wirelesscommunication, and

FIGS. 5 a, 5 b an enlarged portion of the charts as illustrated in FIGS.4 a , 4 b.

It should be understood that the drawings are for purposes ofillustrating the concepts of the disclosure and is not necessarily theonly possible configuration for illustrating the disclosure.

DESCRIPTION OF PREFERRED EMBODIMENTS

It should be understood that the elements shown in FIG. 1 may beimplemented in various forms of hardware, software or combinationsthereof. Preferably, these elements are implemented in a combination ofhardware and software on one or more appropriately programmedgeneral-purpose devices, which may include a processor, memory andinput/output interfaces. Herein, the phrase “coupled” is defined to meandirectly connected to or indirectly connected with through one or moreintermediate components. Such intermediate components may include bothhardware and software based components.

The present description illustrates the principles of the presentdisclosure. It will thus be appreciated that those skilled in the artwill be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of thedisclosure and are included within its spirit and scope.

All examples and conditional language recited herein are intended forinstructional purposes to aid the reader in understanding the principlesof the disclosure and the concepts contributed by the inventor tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions.

Moreover, all statements herein reciting principles, aspects, andembodiments of the disclosure, as well as specific examples thereof, areintended to encompass both structural and functional equivalentsthereof. Additionally, it is intended that such equivalents include bothcurrently known equivalents as well as equivalents developed in thefuture, i.e., any elements developed that perform the same function,regardless of structure.

Thus, for example, it will be appreciated by those skilled in the artthat the block diagrams presented herein represent conceptual views ofillustrative circuitry embodying the principles of the disclosure.Similarly, it will be appreciated that any flow charts, flow diagrams,state transition diagrams, pseudocode, and the like represent variousprocesses which may be substantially represented in computer readablemedia and so executed by a computer or processor, whether or not suchcomputer or processor is explicitly shown.

The functions of the various elements shown in the figures may beprovided through the use of dedicated hardware as well as hardwarecapable of executing software in association with appropriate software.When provided by a processor, the functions may be provided by a singlededicated processor, by a single shared processor, or by a plurality ofindividual processors, some of which may be shared. Moreover, explicituse of the term “processor” or “controller” should not be construed torefer exclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (“DSP”)hardware, read only memory (“ROM”) for storing software, random accessmemory (“RAM”), and nonvolatile storage.

Other hardware, conventional and/or custom, may also be included.Similarly, any switches shown in the figures are conceptual only. Theirfunction may be carried out through the operation of program logic,through dedicated logic, through the interaction of program control anddedicated logic, or even manually, the particular technique beingselectable by the implementer as more specifically understood from thecontext.

In the claims hereof, any element expressed as a means for performing aspecified function is intended to encompass any way of performing thatfunction including, for example, a) a combination of circuit elementsthat performs that function or b) software in any form, including,therefore, firmware, microcode or the like, combined with appropriatecircuitry for executing that software to perform the function. Thedisclosure as defined by such claims resides in the fact that thefunctionalities provided by the various recited means are combined andbrought together in the manner which the claims call for. It is thusregarded that any means that can provide those functionalities areequivalent to those shown herein.

In the following description, example methods for evaluating a wireless(Wi-Fi) link of a wireless node of an access point, e.g. acustomer-premises equipment (CPE) device, or a station are described, aswell as a device performing the methods. For purposes of explanation,various specific details are set forth in order to provide a thoroughunderstanding of preferred embodiments. It will be evident, however, toone skilled in the art that the present disclosure may be practicedwithout these specific details.

A CPE device includes, but is not limited to, for example a controller,e.g. a microprocessor, a memory, in which an operating system is storedfor the operation of the CPE device, a wireless node for a wirelesscommunication, and a circuit for a broadband connection, e.g. an xDSLconnection. The wireless node includes, but is not limited to, asoftware driver, a physical layer with data buffers, and an antenna. ACPE device of this kind is for example an access gateway.

The wireless node is controlled by the software driver which executes anumber of background tasks during operation of the wireless node, e.g.dynamic rate adaptation, packet aggregation, channel quality monitoring,and the like. On top of signal manipulations, the wireless driver alsoembeds an IEEE 802.11 protocol stack with the associated IEEE definedmanagement and control messaging. The wireless driver will hence injecta number of management and control packets in the data stream, making itdifficult to analyze a link by transparently looking at the data frameexchange only.

An arrangement illustrating a wireless communication is schematicallydepicted in FIG. 1 : An access point 1 communicates with a station 2 viaa wireless link 3. The access point 1 includes a circuit comprising amicroprocessor 10, a memory 11, a wireless node 12 for the wirelesslink, and a monitor application 13. The station 2 includes a secondcircuit comprising a microprocessor 20, a memory 21, and a wireless node22 for the wireless link. The wireless node 12 includes a physical layer14 and a link layer 15, and the wireless node 22 includes a physicallayer 24 and a link layer 25. The access point 1 is in particular a CPEdevice, for example a residential gateway establishing with the station2 a home network of an end user. The monitor application 13 is includedfor analyzing and evaluating the wireless link 3 and retrieves inparticular performance parameters of the wireless link 3.

A diagram illustrating an exemplary performance of the wireless link 3according to FIG. 1 is shown in FIG. 2 . A line 30 (“Bandwidth requiredby application”) represents a data rate over the wireless link 3 asrequired by an application included in the station 2, e.g. a videoapplication forcing a video streaming. A line 31 (“Bandwidth available”)represents a data rate that is available over this given wireless link 3at a certain time t. Both rates are expressed in kbit/sec. In theexample shown, there are moments 32 where the available data rate 31 islower than the data rate 30 as required by the application. At thesemoments, the wireless link 3 will limit the data rate provided to theapplication, which might be visible to the end user. This depends on thenature of the application. E.g. for video streaming, typically the videoplayer will implement a jitter buffer which will make short bandwidthlimitations invisible to the end user. As a result, it is difficult tomake a hard prediction about visible end user issues.

The actual data rate of the wireless link 3 is therefore the requireddata rate 30, when there exists sufficient available bandwidth 31, andis equal to the available bandwidth 31, in case the available bandwidth31 is not sufficient for the application. The actual data rate can bemeasured within the access point 1.

A method for determining the available bandwidth 31 is disclosed forexample in the international application WO 2015/044343 of ThomsonLicensing. This application is hereby incorporated by reference.

FIG. 3 shows the example of FIG. 2 , while filling out the actual datarate, 33, dark shaded, and an observed headroom, 34, light shaded,during a monitor or test period 35. It is noted that the monitorapplication typically uses a test period 35 that is longer than thevariations in bandwidth: i.e. the data rate and the headroom ratesavailable in the monitor application typically are averaged numbers ofthe actual data rate 33 and the headroom 34 during the test period 35.This is another reason why the prediction about visible end user issuescannot be “hard”: during a test period of e.g. the end user could havean average available actual data rate 33 of 10 Mbps and an averageheadroom 34 of 2 Mbps, but still have very visible Wi-Fi problems, sincethe available bandwidth 31 is very low during e.g. 10 s within the testperiod of 30 s.

Now, even though no hard predictions can be made with respect to visibleWi-Fi issues, it is possible to estimate the chance that a givensituation, depending on the actual data rate 33 and headroom 34, mightgive rise to a visible Wi-Fi issue. The metric applied here is acalculation defining an assessment function Wxi giving an indication ofa Wi-Fi end-user experience impairment.

There are a few boundary conditions that help to define the functionWxi:

-   -   If the average headroom 34 is zero, this means that the actual        data rate 30 used is clipped to the available data rate 31 for        the whole test period—there is no negative headroom. Given that        the test period typically is in the order of tens of seconds,        the risk for issues visible on the application level are very        high. Let's express the function Wxi in %, which means that this        boundary condition means that Wxi=100% in case of an average        headroom=0 kbps.    -   If there is zero traffic over the wireless link 3, and still        some headroom 34, even if it is small, the risk for visible        Wi-Fi issues is zero: applications are not requiring any        bandwidth at such periods.    -   It is assumed that Wi-Fi issues are independent of the        capabilities, like maximum speed, of the wireless link, but only        dependent on the average actual data rate 33 and the average        headroom 34.

Next to that, there is the requirement that the function Wxi should be asharp, surely non-linear function that emphasizes issues, which allowsto average over a large dataset and still bring out a clear result.

As FIG. 3 indicates, a determining factor for the function Wxi is theratio of the average actual data rate 33 over the average headroom 34,with a correction factor to make sure that not only high data ratesresult in high Wxi values. The following formula can be used to expressthat effect:

${Wxi} = {\frac{( {{{Datarate}( {kbps} )} + {C1}} )}{( {{{Headroom}({kbps})} + {C2}} )} \cdot \frac{C3}{( {{{Datarate}( {kbps} )} + {{Headroom}({kbps})} + {C4}} )}}$

“Datarate”=actual data rate 33, “Headroom”=headroom 34, and withconstants C1-C4 tuned to fulfil above boundary conditions:

C1=C2=C4=500 kbps

C3=50 000 kbps

The function Wxi is used in this embodiment as a truncated integerfunction—to avoid low values below 1 which would introduce noise in longterm averages. Wxi can be averaged over time. If the test period changesover time, this shall be taken into account for the averaging. Thefunction Wxi is calculated for each wireless link. In order to assessthe risk for visible Wi-Fi issues for a given access point, the Wxivalues of all of the different wireless links of the stations beinglinked with that access point are added.

Alternatively, a look-up table can be used instead of the function Wxi,the look-up table taking into account the boundary conditions asdescribed before.

For an embodiment in accordance with FIG. 1 : In case the access point 1is coupled with two or more stations 2 via a respective wireless link,for each wireless link of the access point 1 with a respective station 2an assessment value is calculated, and all calculated assessment valuesare accumulated, to have an indication of the link quality of the accesspoint 1.

Only the bandwidth available on the access point 1 is not a good metricfor indicating, flagging or bringing out Wi-Fi problems that arereducing the end user experience, in particular for problems where thewireless link is the bottleneck for the bandwidth available to theapplications that the end user is using. For example, the bandwidth of agiven wireless link might be drastically reduced by an interferer from100 Mbps to 5 Mbps, wherein the end user is still perfectly happy sincethe application he is using, e.g., audio streaming, is not affected bythe interference.

The method uses the notion of the headroom 34—the bandwidth availablebut not used by the wireless link—and combines this with the actual datarate 33—i.e. the bandwidth used by an application. This requires toinclude the available data rate 31, which can be obtained, for example,by using a passive monitoring of the wireless link 3. Lack of headroomat moments when an application is consuming bandwidth indicates that thewireless link has become the bottleneck, which risks to be visible tothe end user on application level. Therefore, the described method isdefined by using both the actual data rate 33 and the headroom 34. Withthe method, it is possible to detect Wi-Fi problems affecting end usersatisfaction, and allows therefore to concentrate on real visible Wi-Fiproblems rather than just trying to increase the bandwidth of thewireless link, also in cases where no visible Wi-Fi problems occur. Withan appropriate back end infrastructure, it has now become possible for anetwork service provider to closely monitor the performance of awireless link of an end user by using the described method. A knowledgeof which applications are running on the site of the end user is notrequired, the method does not make assumptions on that. With the method,a metric is given which tries to estimate the risk for “a generalapplication”.

FIGS. 4 a, 4 b show an example of how the function Wxi reflects visibleWi-Fi issues. The top diagram, FIG. 4 a , shows monitoring results of aWi-Fi link between a residential gateway and a Play Station 3 that isused to watch Netflix movies. The monitoring graph uses the same colourscheme as the examples given before: dark shaded is the actual data rate33, and light shaded is the headroom 34. Test period in this case is 30s. On the left side of FIG. 4 a , the buffering and the streaming of afirst episode is depicted, time marks 1-277. On the right side of FIG. 4a , time marks 283-571, a second episode is buffered and streamed.

The second diagram below, FIG. 4 b , shows Wxi values according to theformula given above. For the first episode, at the beginning, theheadroom 34 is getting smaller during the initial buffering 40,indicated by non-zero, yet small Wxi values 43: the Wi-Fi conditionshere are affecting the time needed for buffering. After buffering, timemarks 25-277, sufficient headroom 34 is available, and the Wxi valuesare about zero. During the second episode, however, far-end interference41, dark columns, is present and is reducing the headroom from time totime, both during buffering, time marks 283-313, and during subsequentstreaming. The effects of that are visible to the end user, andreflected by high Wxi values 42, sometimes up to 100%, indicating thatthe bandwidth is limited by the Wi-Fi interference during the entire 30s test period.

The final part of FIGS. 4 a, 4 b with the time marks 391-571 is enlargedand depicted in FIGS. 5 a, 5 b . As can be seen, the high Wxi values 42are essentially caused by high far-end interference values 41.

Also other embodiments of the present disclosure may be utilized by oneskilled in the art without departing from the scope of the presentdisclosure. The method as described may be used in particular for allkinds of access points using a wireless transmission, e.g. in accordancewith IEEE 802.11. The present disclosure resides therefore in the claimsherein after appended.

Although embodiments which incorporate the teachings of the presentdisclosure have been shown and described in detail herein, those skilledin the art can readily devise many other varied embodiments that stillincorporate these teachings. Having described preferred embodiments(which are intended to be illustrative and not limiting), it is notedthat modifications and variations can be made by persons skilled in theart in light of the above teachings. It is therefore to be understoodthat changes may be made in the particular embodiments of the disclosuredisclosed which are within the scope of the disclosure.

1. A method implemented by an Access Point (AP), the method comprising:monitoring, from the AP, a wireless link between a station and the APfor a set of test periods, wherein the set of test periods comprisesmore than one test periods, wherein at least a first test period of theset of test periods is a different length of time than a second testperiod; wherein the monitoring comprises measuring a used bandwidth onthe wireless link over each test period of the set of test periods,wherein the AP is an 802.11 AP that is part of a 802.11 wireless localarea network (WLAN); averaging the used bandwidth over each test periodof the set of test periods to determine an actual data rate of thewireless link for each test period of the set of test periods;determining an available data rate of the wireless link based on anaverage of an available bandwidth over each test period of the set oftest periods for each test period of the set of test periods;calculating a headroom rate for each test period of the set of testperiods based on the actual data rate and the available data rate foreach test period of the set of test periods; calculating an assessmentvalue for each test period using a look up table or a formula, thecalculating based on the actual data rate and the headroom rate;averaging each assessment value for each test period of the set of testperiods to generate an averaged assessment value of the set of testperiods for the wireless link; determining an indication of a quality ofthe wireless link based on the averaged assessment value; and sendingthe indication of quality of the wireless link based on the averagedassessment value to a service provider of the AP outside of the WLAN ofthe AP.
 2. The method of claim 1, wherein each test period is greaterthan 10 seconds.
 3. The method of claim 1, wherein each test period islong enough such that the available bandwidth varies more than athreshold.
 4. The method of claim 1, wherein each test period is longenough such that the used bandwidth varies more than a threshold.
 5. Themethod of claim 1, wherein the headroom rate is further based on adifference between the available data rate and the actual data rate ofthe wireless link.
 6. The method of claim 1, further comprising:calculating an averaged second assessment value for each test period ofthe set of test periods based on a second actual data rate and a secondheadroom rate of a second wireless link, wherein the second wirelesslink is between the AP and a second station, wherein the indication of aquality of the wireless link is determined based on the averagedassessment value and the second averaged assessment value.
 7. An accesspoint, the access point comprising: a transceiver and a processor, thetransceiver and processor configured to monitor a wireless link betweena station and the AP for a set of test periods, wherein the set of testperiods comprises more than one test periods, wherein at least a firsttest period of the set of test periods is a different length of timethan a second test period; wherein the monitoring comprises measuring aused bandwidth on the wireless link over each test period of the set oftest periods, wherein the AP is an 802.11 AP that is part of a 802.11wireless local area network (WLAN); the transceiver and processorconfigured to average the used bandwidth over each test period of theset of test periods to determine an actual data rate of the wirelesslink for each test period of the set of test periods; the transceiverand processor configured to determine an available data rate of thewireless link based on an average of an available bandwidth over eachtest period of the set of test periods for each test period of the setof test periods; the transceiver and processor configured to calculate aheadroom rate for each test period of the set of test periods based onthe actual data rate and the available data rate for each test period ofthe set of test periods; the transceiver and processor configured tocalculate an assessment value for each test period using a look up tableor a formula, the calculating based on the actual data rate and theheadroom rate; the transceiver and processor configured to average eachassessment value for each test period of the set of test periods togenerate an averaged assessment value of the set of test periods for thewireless link; the transceiver and processor configured to determine anindication of a quality of the wireless link based on the averagedassessment value; and the transceiver and processor configured to sendthe indication of the link quality of the wireless link based on theaveraged assessment value to a service provider of the AP outside of theWLAN of the AP.
 8. The AP of claim 7, wherein each test period isgreater than 10 seconds.
 9. The AP of claim 7, wherein each test periodis long enough such that the available bandwidth varies more than athreshold.
 10. The AP of claim 7, wherein each test period is longenough such that the used bandwidth varies more than a threshold. 11.The AP of claim 7, wherein the headroom rate is further based on adifference between the available data rate and the actual data rate ofthe wireless link.
 12. The AP of claim 7, wherein the transceiver andprocessor are further configured to: calculate an averaged secondassessment value for each test period of the set of test periods basedon a second actual data rate and a second headroom rate of a secondwireless link, wherein the second wireless link is between the AP and asecond station, wherein the indication of a quality of the wireless linkis determined based on the averaged assessment value and the secondaveraged assessment value.